An incredibly soft, fluffy, and nutrient-dense sandwich loaf that perfectly repurposes leftover liquid whey from home yogurt or cheese production. By pairing the moisture-retaining Japanese Yudane method with the structural and tenderizing benefits of acidic whey proteins, this bread yields a cloud-like crumb that stays fresh for days.
At 8:00 AM, place 130g of bread flour into a small bowl and pour 130g of boiling water directly over it. Stir vigorously with a sturdy spoon until all dry spots disappear and a thick, sticky dough paste forms. Cover tightly and let it sit to cool down to room temperature before adding it to the main mix.
Step 2 - Mixing & Bulk Proofing
First Mix: At 8:30 AM, add the room-temperature liquid whey, egg, instant yeast, sugar, 520g bread flour, and salt into your stand mixer bowl. Tear the cooled Yudane paste into several smaller pieces and drop them straight into the bowl.
Knead Phase 1: Attach your dough hook and mix on a low speed (or KitchenAid speed 3) for 5–6 minutes. The ingredients should come together into a uniform, tacky mass that wraps itself cleanly around the hook.
Enrich: Add the 80g of softened butter to the bowl. Increase the mixer speed to medium-high and continue kneading for 10–15 minutes. The dough will look messy initially but will gradually transform into an ultra-smooth, glossy, and highly elastic ball that cleanly passes the windowpane test.
Bulk Rise: Form the dough into a smooth ball, place it in a greased bowl, cover tightly, and let it proof for 2 hours at 76–80°F (24–28°C) until light, airy, and visibly puffy.
Step 3 - Shaping & Staged Baking
Roll Out: At 10:30 AM, lightly dust your workspace with flour. Tip out the puffy dough and use a rolling pin to flatten it into a large rectangle. Ensure the narrowest edge of the rectangle matches the length of your 13-inch loaf pan.
Shape: Starting from the short edge, roll the dough up tightly into a dense cylinder. Place the log seam-side down into a greased baking pan.
Final Proof: Cover loosely and let it proof for 1 to 2 hours at 76–80°F (24–28°C) until the crown of the expanding dough rises to exactly half an inch below the top rim of the pan.
Bake Staged: Preheat your oven to 375°F (190°C). Slide the pan in and bake for 15 minutes. Lower the oven temperature to 350°F (175°C) and continue baking for 20–25 minutes until the crust is a uniform, deep golden brown. Remove immediately from the pan and cool completely on a wire rack.
Egg-Free Substitutions: If you cannot consume eggs or want to make this recipe egg-free, you can easily omit the egg completely. To maintain the recipe's exact hydration balance, simply replace the weight of the egg by adding an extra 50g of liquid whey or standard whole milk to the initial dough mix.
Substituting Liquid Whey with Milk: If you run out of homemade whey, you can substitute it with an equal weight of standard whole milk or buttermilk. While milk will still produce a beautifully soft loaf due to the Yudane roux, using whey adds an extra punch of natural enzymes and lactic acidity that weakens harsh gluten bonds, yielding an even tenderer bite.
Converting to a Sourdough Base: To naturally leaven this bread, omit the 5g of commercial instant yeast. Instead, add 140g of an active, bubbly sourdough starter (or sourdough discard if you are looking for a gentle rise with a tangier profile) directly into the main dough mix. Keep in mind that your bulk and final pan proofing times will extend significantly—plan for roughly 4 to 6 hours for each phase depending on your room temperature.